Babies work hard to get ready to talk. They listen intently, and at around 6 months of age start to babble with passion while their brains figure out how to make sounds understood by others. A new study suggests babies might also learn to gab by using their eyes. Months before their babble becomes real words, babies watch people’s lips as they talk.

“Babies start to lip-read when they learn to babble,” David Lewkowicz, a psychologist who worked on the study, told Science News. At that ...